[labnetwork] Thermal load in cleanrooms ISO 5/6

Tue Mar 17 10:13:33 EDT 2015

Dear Jim,

I like the idea of  a single external Chiller. This should be fine for 
most of our tools. However a few equipments are more sensitive demanding 
higher flow and or pressure...

The combination an external chiller and a few smaller ones line could be 
the best solution for us, having a small backup chiller in case of 
urgent need...

I am curious to know the number of technicians you have in a facility 
with 40-50 tools...
Here, ww can afford only one  ;-/

best,
Loïk.

Le 16/03/2015 17:25, Beall, James A. a écrit :
> Loïk,
>
> I agree with the caution about accounting for the heat from the FFU; 
> it is significant.
>
> In our fabs we use a large external Process Chilled Water unit which 
> provides cooling for 40-50 tools. Some of the equipment (like cryopump 
> compressors and larger pumps which typically have larger => 3/8” 
> diameter), cooling lines can be directly cooled by the PCW loop. Many 
> other tools like electron gun evaporators and sputter guns have 
> smaller cooling lines and you may have trouble directly connecting 
> them to the PCW loop and achieving the required flows and pressures.
>
> We end up with many small heat exchangers each set up for the 
> particular needs of our tools. Some run distilled water, some DI 
> water, some glycol and some high temperature thermal fluids. The pumps 
> are the weak point in these units.
>
> When connecting tools across your PCW loop be careful to include 
> balancing or flow setting valves as you will have many connections in 
> parallel.
>
> Also I prefer to use a non-closed system, i.e., one with an 
> atmospheric pressure return tank. This can be automatically refilled 
> with treated water as needed to account for leaks and losses. Having 
> your return water dump into a non-pressurized tank creates much less 
> back pressure than the closed loop pressurized systems. The back 
> pressure can be a killer with many parallel connected tools with 
> different impedances.
>
>
>   - Jim
>
>
>
> On Mar 16, 2015, at 11:41 AM, Iulian Codreanu <codreanu at udel.edu 
> <mailto:codreanu at udel.edu>> wrote:
>
>> Loik,
>>
>> Another thing to keep in mind is the heat that is "taken away from 
>> the equipment" via exhaust.
>>
>> The heat generated by a piece of equipment can:
>> -Be dissipated into the room
>> -Be "taken away" by the cooling water.
>> -Be "taken way" by exhaust.
>>
>> If a piece of equipment is not cooled and does not have exhaust then 
>> all the heat gets dissipated into the room.
>>
>> If the piece of equipment is cooled and exhausted only part of the 
>> heat generated will end up in the room.
>>
>> If you know how much heat is taken away by the cooling water and/or 
>> exhaust that is great.  If you do not, I saw engineers using factor 
>> such as (PCW stands for process cooling water):
>> 100% of the power into  the room if no PCW and no exhaust
>> 50% of the power into  the room is no PCW but exhaust
>> 40% of the power into  the room if PCW but no exhaust
>> 20% of the power into  the room if both PCW and exhaust
>>
>> I prefer the "unique chiller (placed outside of the building)" 
>> approach for cooling the equipment.  If you can run the water from 
>> the unique chiller directly through the equipment, you do not have to 
>> deal with the heat generated by the "small chillers".
>>
>> Iulian
>>
>>
>>
>> iulian Codreanu, Ph.D.
>> Director of Operations, UD NanoFab
>> 163 ISE Lab
>> 221 Academy Street
>> Newark, DE 19716
>> 302-831-2784
>> http://udnf.udel.edu
>> On 3/16/2015 10:36 AM, Loïk GENCE wrote:
>>> Hi Everyone,
>>>
>>> I am working on the design of a small cleanroom facility (70m2) ISO 
>>> 5/6. Right now, I am dealing with the problem of thermal load,
>>> Which is crucial here in Rio, where the average outside temperature 
>>> is of 30 deg C with a relative humidity of 75-80 %.
>>>
>>> I would like to have your help and/or comments on several points:
>>>
>>> Most of the manufacturers do not provide a value for the thermal 
>>> load (why?). Assuming 2 or max 3 people working simultaneously in 
>>> the cleanrooms, and usual cleanroom value: 22 deg C - 55% humidity. 
>>> The main issue is: how can I estimate the cooling power required for 
>>> the Air Conditioning System (ACS)?
>>>
>>> I have the list of equipments we'll have and the corresponding 
>>> electrical power. I assumed the heat generated by 2 users and added 
>>> the total electrical power dissipated as heat inside of the 
>>> cleanroom, using a simultaneity factor of 0.75 (all equipments won't 
>>> be turned on at the same time) and neglected the heat produced by 
>>> the filter fan and lightning.
>>> ***
>>> **        - Is it reasonable for dimensioning the ACS cooling power ? *
>>>
>>> Also most of the equipments have a cooling water circuit. But the 
>>> cooling power needed is well described in the installation manual 
>>> provided with the equipments.
>>>
>>> *        - Should I subtract from the **ACS cooling power**value, 
>>> **the cooling po**wer **from the chillers?*
>>>
>>>         - *Do you think a central and unique chiller (placed outside 
>>> of the building) is preferred to several smaller chillers placed 
>>> closer to the equipment?*
>>>
>>>
>>> I thank you very much for your kind help or comments.
>>>
>>>
>>> regards,
>>>
>>> Loïk.
>>>
>>> -- 
>>> __________________________________________
>>> Dr. Loïk Gence
>>>
>>> PUC-RIO/CETUC-LABSEM
>>>
>>> End Rua Marques de São Vicente, 225-Gavea
>>> CEP:22451-900   Rio de Janeiro, RJ-Brasil
>>>
>>>        (Telefone)      +55 (021) 3527-2193
>>>
>>> 	(Mobile)     +55 (021) 99156-5558
>>>
>>> loik.gence at cetuc.puc-rio.br
>>> __________________________________________
>>>
>>>
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>>
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-- 
__________________________________________
Dr. Loïk Gence

PUC-RIO/CETUC-LABSEM

End Rua Marques de São Vicente, 225-Gavea
CEP:22451-900   Rio de Janeiro, RJ-Brasil

       (Telefone)      +55 (021) 3527-2193

	(Mobile)     +55 (021) 99156-5558

loik.gence at cetuc.puc-rio.br
__________________________________________

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